Fluid coupling

ABSTRACT

An improved fluid coupling permitting relative rotation between two rotatable fluid-tight seal elements, having confronting annular fluid-tight surfaces, maintained in a fluid-tight relationship by axial compression of a length of elastic tubing forming one of the fluid connections to said seal elements.

Unlted States Patent 1 1 1111 3,801,142

Jones et al. Apr. 2, 1974 [54] FLUID COUPLING 3,195,931 7/1965 Braunagel285/375 x 3,122,375 2/1964 Grecnwald 277 88 [75] Inventors: Alan L.Jones, Endv/ell, George T. 2,805,086 9,1957 shumaketw 285/279 X whlmeyPoll; Robe" 3,201,135 8/1965 Hayatian.... 277 92 Kellogg, Endwell, allof NY 2,890,901 6 1959 Martin 277/88 x 2,779,611 1 1957 w 1 .1 277 92 x[73] Assgnee Busness Machmes 3,391,942 7/1968 1 277/96 R x Armonk,2,662,480 12 1953 Cliborn 277/88 x [22] Filed: June 30, 1972 PrimaryExaminer-Thomas F. Callaghan [21] Appl' NO" 267815 Attorney, Agent, orFirm-Paul M. Brannen [52] [1.8. CI 285/280, 233/1 A, 285/375 [57]ABSTRACT 51 1111. c1. F16] 27/00, B04b 7/00 [53] Field of Search285/280, 279 231, 9 375; An 1mproved fluid couphng perm1tt1ng relativerota- [56] References Cited UNITED STATES PATENTS 3,565,330 2/1971Latham 277/88 X 3,460,857 8/1969 Larkin 277/88 X tion betweentworotatable fluid-tight seal elements, having confronting annularfluid-tight surfaces, maintained in a fluid-tight relationship by axialcompression of a length of elastic tubing forming one of the fluidconnections to said seal elements.

1 Claim, 4 Drawing Figures PATENTEMPR 2 i974 SHEEY 2 BF 2 FLUID COUPLINGBACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates broadly to fluid coupling devices and particularly to animproved fluid coupling device permitting relative rotation between twofluid conduits or tubes, with no leakage in the coupling.

2. Description of the Prior Art There are many fluid coupling devicesknown in the prior art, but most of these require a large number ofparts, or are composed of materials which are not suited to use inhandling particular fluids or in particular environments. Typical of theprior art is US. Pat. No. 2,459,201 issued to T. R. Thomas. This sealstructure provides a fluid-tight rotating seal, but requires a pluralityof elements and contemplates a grease seal or other material to providea fluid-tight coupling. In uses where the coupling must be simple andeconomical, as in one time or expendable uses in connection with fluidsystems handling human blood, the prior art does not offer a devicewhich is economical, easily sterilized, and not adversely affected bythe environment, and, on the other hand, having no deleterious effectson the fluid being handled. The seal structure shown herein is also animprovement over that disclosed and claimed in a co-pending applicationfor Letters Patent of the United States, Ser. No. 231,620, filed on Mar.3, 1972, now abandoned, and assigned to the same assignee as thisapplication.

SUMMARY OF THE INVENTION The present invention solves the problemsrecited above by providing a fluid coupling comprising only a fewelements, each of which can be made of material suited to the fluid tobe handled, and economical enough to be expendable.

Accordingly, it is a principal object of the invention to provide animproved fluid coupling having a minimum number of parts and especiallyadapted to have an inert effect on the fluid to be handled.

Another object of the invention is to provide an improved fluid couplingdevice which is sufficiently economical in parts as to be disposableafter a single use.

The invention contemplates a pair of seal elements having confrontingannular fluid-tight sealing surfaces,

of non-corrodable material maintained in a rotatable but fluid-tightrelationship by axial compression of a length of elastic tubing formingone of the fluid connections to said seal elements.

The foregoing and other objects, features and advantages of theinvention will be more apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic illustrationof a perspective view of a preferred embodiment of the invention;

FIG. 2 illustrates a front elevational view of the device shown in FIG.1;

FIG. 3 is a top view of the device shown in FIG. 1, and

FIG. 4 is a cross-sectional elevational view of the device shown in FIG.1.

Similar reference characters refer to similar parts in each of theseveral views.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings, FIG. 1shows a perspective diagrammatic view of a preferred embodiment of theinvention, showing the apparatus in its operative relation to a bloodwashing apparatus with which it is particularly designed to cooperate.The centrifuge mechanism indicated generally by reference character 3 isarranged to contain a flexible blood container, provided with a centralcollar 5 and inlet tube 7, by which blood to be processed along withother solutions may be admitted to or recovered from the processing bagwhile the centrifuge is in operation. Centrally positioned over the tube7 and on the axis of the rotation of the centrifuge is the seal body 9,which has an outer body having an outer surface which is non-circular toprevent rotation. In a preferred form of the invention, the seal body ishexagonal in form as shown. A weight 11 is provided which is arranged tobe freely movable up and down on two supporting members such as thebolts 13 and 15. In the position shown, the weight will exert a downwardforce on the uppermost face of the seal body 9, to thereby transmit asealing force through the internal parts of the seal in the manner to besubsequently explained. From the top of the seal 9, a non-rotating hoseor tubing 17 extends to the remainder of the apparatus containing thewashant solutions and the necessary connections and plumbing to operatethe apparatus, none of which is shown in detail since it forms no partof the invention. The bolts 13 and 15 are retained in a cover element19, which is one of a pair of slidable covers, which, when opened,provide access to the centrifuge for the purpose of inserting orremoving the blood container. When the covers are slid to the closedposition, then the seal may be supported and restrained by weight 11.

The relationship of the seal element 9 to the weight 11 and thesupporting studs or bolts 13 and 15 can also be seen in FIG. 2 of thedrawings, which constitutes an elevational diagrammatic view of theapparatus. It will be noted that the openings in the weight assembly 11are counterbored to the extent that the weight 11 can be raisedsufficiently far to clear the seal 9 during the time that the seal andthe associated blood bag are being installed or removed from thecentrifuge.

FIG. 3 is a top or plan view illustrating the relationship of the sealbody 9 and the weight 11. It will be noted that the seal 9 is hexagonalin its cross-sectional shape, as well as the recess in the weight 1 1.Thus the seal body 9 is prevented from rotating by the engagement of thenon-circular outer surfaces of the seal and the mating surfaces in thereceiving cavity in weight 1 1 FIG. 4 is a diagrammatic elevationalview, partly in cross-section, of the seal body and its associatedparts, showing the internal structure of the seal.

As shown in FIG. 4, the fluid path includes the flexible tube 17, whichis fitted onto a seal housing adapter 21. At the lower end of thehousing adapter 21 there is provided a link of highly flexible tubing23, such as surgical rubber tubing, which in turn connects with a firstseal element 25, preferably made of suitable ceramic material. The firstseal element confronts a second seal element 27 which has attachedthereto a rigid plastic tubing section 29, and then a connecting link ofhighly flexible tubing 31, which is attached to the blood bag in thecentrifuge by means of the tubing 7 and the collar 5. The tubing 7extends through the collar 5 and projects into the interior of the bag33. The end of tubing 7 is notched 35 to allow the flow of fluids intoand out of the bag. This extension of tube 7 provides a minimumclearance between the top and bottom of the bag, even when a force isexerted on the bag, so that flow can freely take place between theremainder of the bag and the collar 5 and tubing 7.

The function of the seal is to allow entry and removal of fluids,particularly blood and wash solutions, but also supernatant fluids thatare originally in the blood, such as plasma, or in the case of frozenblood, the cryoprotective agents added before freezing, with this entryoccurring sometimes with the blood bag being stationary in thecentrifuge, and sometimes while it is being oscillated back and forth,and still other times when it is cqr tinuouslyspinning at speeds up to3300 rpm T l 1 e seal must operate at reasonable pressures, for example,eight pounds per square inch or more, at rotational speeds up to 3,300rpm without lubrication and also without causing temperature rise of therotating parts beyond 30 F. above ambient.

The seal must also assure no loss of blood nor allow any opening whichwould make the blood or the solutions nonsterile, both while it is instorage and while it is in use. At the same time, the manufacturingtolerances for the plastic blood bags are such that the seal mustfunction even when the bag collar and stem and the bag are notconcentrically located under the stationary upper half of the seal.

These objectives are obtained by the present structure as follows. Thetwo seal elements 25 and 27 are lapped optically flat on their matingfaces. The faces may or may not be coated with a suitable siliconcomposition to provide fluid repellency. The two seal elements are thenassembled and spring-loaded together by the following steps: Seal half27 and tube 29 are pressed together to form an assembly. The sealbearing assembly 37 is pressed into the seal housing 9. This sealbearing assembly is made of a felt ring supported in a housing of metalor other rigid material, and. acts as a bearing which by its compositiondoes not require lubrication, does not overheat the plastic tube 29 andyet supports and guides the lower rotating seal element 27. Additionallyit has the capacity to absorb and retain any minor fluid weepage thatmay occur at the seal faces, thus acting as both a bearing and asecondary sealing device.

Seal element 27 and tubing 29 are dropped from above into the bearing37; then a second subassembly consisting of the adapter 21, the flexibletubing 23 and the upper seal element 25 are dropped into the housing.Next an axial force equal to approximately 0.6 pound is applied to theadapter 21. This force compresses the flexible latex tube 23 whichthereafter serves in the function of a spring to load the two faces ofthe ceramic seal elements 25 and 27 together. Adapter 21 is thencemented into the housing 9 by a quick acting cement or by heat actingon the thermal plastic. With the seal thus assembled, the confrontingfaces of the ceramic seal elements are preloaded together by a 0.6 poundload by reason of the fact that the underside of the rotating ceramicseal element 27 is pushed up against the upper face of the felt bearingseal 37. At this time it should be noted that the flexible tubing 23 notonly acts to provide the necessary spring force, but also carries thetorque caused by friction at the rotating faces of the ceramic sealelements 25 and 27. Also it is essential that the tubing section 23 beflexible to allow the stationary ceramic seal element 25 to rock andoscillate as is required if it is to follow the perturbations of thelower seal element 27 that occur due to the previously discussedeccentricities in the blood bag and its associated stem.

When the bag stem tubing 7 and the entrance tube 17 are attached to theseal, the seal is at that time closed by the 0.6 pound load and thus iseffective in maintaining sterility within the system as well aspreventing fluid leaks if the associated bag is full of fluid. Animportant feature of the present invention is that if a pull force isexerted on the bag stem or on the entry tube, the force so appliedcannot act to pull the seal faces open. The force thus applied goes fromthe seal adapter 21 to the seal body 9, thence to the seal bearing 37,to the tube 29 and the flexible tubing 31, but bypasses the flexibletubing 23 and upper seal element 25.

Tubing section 31 must also be sufficiently flexible to allow the bagand stem to wobble due to the lack of concentricity and yet havesufficient stiffness to carry the required torque and yet not transmitside load due to the wobble that would otherwise tend to open the sealfaces during high speed rotation.

In use, the associated bag and seal assembly and the entry tube 17, allassembled as a unit, will be installed in the centrifuge bowl, and thenthe weight I l or some other suitable force such as a suitably confinedspring force is applied to produce one to two pounds force at the upperend of the seal housing 9.

The load applied at the top of the seal body or housing 9 is transmittedaxially down through the seal assembly causing the bag under the stem tobe pressed down against a portion of the centrifuge bowl within which itis disposed. As previously pointed out, the projection of tubing 7 inthe bottom of the adapter collar will keep the fluid path into the bagopen. The lto 2- pound force on the seal housing serves two purposes.First it brings the unit pressure on the faces of the rotating sealelements 25 and 27 up to a level that will seal fluids at pressures upto 8 pounds per square inch or more, and secondly, it further compressesthe flexible tubing 23 with the result that the lower ceramic element 27rises up off its contact with the seal bearing element 37, and thereforeit does not rub against the seal bearing element during rotation. At thesame time the seal bearing element 37 guides the lower ceramic sealelement 6 loosely but sufficiently accurately to prevent its outsidediameter from rubbing on the inside diameter of the seal housing 9. Alsobecause there is clearance at the outside diameter of the seal element27 it is entirely free to rock as much as may be dictated by theeccentricity of the stern and bag. The upper seal element is somewhatlarger in diameter, as can be seen from the drawings, so that it isguided by the inner diameter of the seal housing 9. However, the fit issuch that it is free to move up and down under the influence of theaxial load and also sufficiently free that it can rock and wobble asrequired to stay in intimate contact with the other ceramic sealelement.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade a first section of flexible elastic tubing disposed within saidseal body, having one end thereof connected to one of said sealelements,

a seal adapter element fixed in said seal body and having an axial boretherethrough, and a portion connected to said flexible tubing section,

means for supporting said ceramic seal elements within said seal body,

means for applying a compressional force to said ceramic seal elementsby axially compressing said flexible elastic tubing comprising a weightwhich rests on said seal body when the coupling is operative, saidweight having a non-circular cavity for receiving said seal body in anon-rotatable relationship, and having a slotted portion admitting atubing connection to said body, and

a second elastic tubing section external to said seal body forestablishing a fluid connection to the seal element confronting theelement connected to the section of elastic tubing within the seal body.

1. A rotatable fluid coupling comprising, in combination, a hollow sealbody having a non-circular periphery and having an axially-alignedcavity therein, a first and a second ceramic seal element disposed insaid cavity, said seal elements having confronting annular surfaceslapped to a fluid-tight smoothness, a first section of flexible elastictubing disposed within said seal body, having one end thereof connectedto one of said seal elements, a seal adapter element fixed in said sealbody and having an axial bore therethrough, and a portion connected tosaid flexible tubing section, means for supporting said ceramic sealelements within said seal body, means for applying a compressional forceto said ceramic seal elements by axially compressing said flexibleelastic tubing comprising a weight which rests on said seal body whenthe coupling is operative, said weight having a non-circular cavity forreceiving said seal body in a non-rotatable relationship, and having aslotted portion admitting a tubing connection to said body, and a secondelastic tubing section external to said seal body for establishing afluid connection to the seal element confronting the element connectedto the section of elastic tubing within the seal body.